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Transcript
Chapter 15: Sense Organs
PowerPoint by John McGill
Supplemental Notes by Beth Wyatt
I.
SENSORY RECEPTORS
(Receptors)
Distal Ends of
Dendrites of Afferent
Neurons
Located in Sense
Organs
1
SENSORY RECEPTORS
GENERAL FUNCTION
Receive Stimulus(Detect Change)
Convert Stimulus to NI (NI Begins at
Receptors)
The Nervous Impulse (NI) Is Carried Along
Afferent Neuron into CNS; Once in CNS the
Result May be
1) Sensation and/or
2) Reflex
SENSORY RECEPTORS
CHARACTERISTICS
1. SPECIALIZED
Each Receptor Responds Best to a Particular
Stimulus
2. EXHIBIT ADAPTATION
In Response to a Continuous Stimulus, Receptors
Becomes Less Sensitive ---> Conduct Fewer
NI ---> Perception of Sensation Decreases
Adaptation Time Varies with Receptor
2
SENSORY RECEPTORS
CLASSIFICATION
BASED STIMULUS TYPE
THAT ACTIVATES
RECEPTOR
1. MECHANORECEPTORS
(Pressoreceptors)
pressure
2. CHEMORECEPTORS
3. THERMORECEPTORS
chemicals
temperature
4. NOCICEPTORS
5. PHOTORECEPTORS
Pain (tissue damage)
light
SENSORY RECEPTORS
Mechanoreceptors
Pressoreceptors
Activated by a Stimulus That Deforms or Changes the
Position of the Receptor
Example: Pressure Receptors
3
SENSORY RECEPTORS
CHEMORECEPTORS
Activated by Chemicals
Example: Smell, Taste Receptors
SENSORY RECEPTORS
THERMORECEPTORS
Activated by Hot/Cold
Example: Hot, Cold Receptors in Skin
4
SENSORY RECEPTORS
NOCICEPTORS
Activated by Intense Stimulus That Causes Tissue Damage
Example: Pain Receptors
5
PAIN
SENSORY RECEPTORS
PHOTORECEPTORS
Activated by Light
Example: Vision Receptors
6
LOCATION & TYPES
Receptors Are Located in Sense Organs
2 Kinds of Receptors
RECEPTORS RESPONSIBLE FOR GENERAL
(SOMATIC) SENSES
RECEPTORS RESPONSIBLE FOR SPECIAL
SENSES
FOUND IN SPECIAL SENSE ORGANS
Nose, Tongue, Ears, Eyes
RECEPTORS RESPONSIBLE FOR
GENERAL (SOMATIC) SENSES
FOUND IN GENERAL SENSE ORGANS
Skin,
Mucous Membranes, Connective
Tissues, Muscles, Tendons, Joints, Viscera
TYPES (Based on Location)
EXTEROCEPTORS
VISCEROCEPTORS
PROPRIOCEPTORS (Special Type of
Visceroceptors)
7
GENERAL SENSE ORGANS:
EXTEROCEPTORS
Lie Close to the Body's
Surface (Skin, Mucous
Membranes,
Connective Tissues)
Respond to External
Stimuli
Responsible for Hot,
Cold, Pressure, Pain,
Touch
Thermoreceptor
GENERAL SENSE ORGANS:
VISCEROCEPTORS
Located Within the
Viscera
Respond to Internal
Stimuli
Responsible for
Sensations in
Organs: Hunger,
Nausea, Thirst, Pain
in Organs, etc.
8
RECEPTORS RESPONSIBLE
FOR GENERAL (SOMATIC)
SENSES
PROPRIOCEPTORS
(Special Type of
Visceroceptors)
Located in Muscles,
Tendons, and Joints
Responsible for
Kinesthesia
(Proprioception)
RECEPTORS RESPONSIBLE
FOR SPECIAL SENSES
FOUND IN SPECIAL
SENSE ORGANS
Nose, Tongue, Ears,
Eyes
TYPES
OLFACTORY
RECEPTORS
TASTE BUDS
HEARING/EQUILIBRIU
M RECEPTORS
VISION RECEPTORS
9
OLFACTORY RECEPTORS
Located Within
Nose
(Receptors for
Cr. Nerve I)
Responsible
for Smell
TASTE BUDS
Located on the
Surface of the
Tongue (Receptors
for Cr. Nerves VII
and IX)
Responsible for
Taste
10
HEARING/EQUILIBRIUM
RECEPTORS
Located Within Inner Ear (Receptors for Cr. Nerve VIII)
Responsible for Hearing and Equilibrium
VISION RECEPTORS
Located Within Eye
(Receptors for Cr.
Nerve II)
Responsible for
Vision
11
SENSE OF HEARING AND
BALANCE: THE EAR
STRUCTURE (3
Divisions)
EXTERNAL EAR
MIDDLE EAR
INNER EAR
EXTERNAL EAR
AURICLE
(PINNA)
Appendage
Attached to the
Side of the Head
EXTERNAL
AUDITORY
MEATUS (Ear
Canal)
12
MIDDLE EAR:
TYMPANIC MEMBRANE
Eardrum; Separates
External from Middle Ear
MIDDLE EAR:
TYMPANIC MEMBRANE
Eardrum;
Separates
External from
Middle Ear
http://www.entusa.com/eardrum_and_
middle_ear.htm
13
MIDDLE EAR:
AUDITORY BONES
MALLEUS, INCUS, STAPES (All Connected)
OPENINGS INTO
MIDDLE EAR
FROM EXTERNAL EAR: EXTERNAL AUDITORY MEATUS
COVERED BY TYMPANIC MEMBRANE
FROM INNER EAR
FROM EUSTACHIAN TUBE
a. OVAL WINDOW: STAPES FITS HERE (& COVERED BY
MEMBRANE)
b. ROUND WINDOW: COVERED BY MEMBRANE
Eustachian Tube: Direct Opening into Middle Ear from Throat
(Behind Nose)
Function: Equalizes Pressure in Middle Ear
FROM MASTOID SINUSES
Located in Mastoid Processes (Temporal Bones)
Also Direct Openings into Middle Ear
14
INNER EAR (LABYRINTH)
Inner Ear is Composed of
Bone (Bony Labyrinth) and
Membrane (Membranous
Labyrinth)
Membranous Labyrinth is
Located Within the Bony
Labyrinth
BONY LABYRINTH (3
Regions)
VESTIBULE: Central
COCHLEA: Snail’s Shell
SEMICIRCULAR
CANALS: 3 Canals That
Lie At Right Angles to
One Another
15
MEMBRANOUS LABYRINTH:
Fits Inside Bony Labyrinth;
4 Regions
UTRICLE,SACCULE
(WITHIN VESTIBULE)
COCHLEAR DUCT
(WITHIN COCHLEA)
Contains Equilibrium
Receptors
Contains Hearing
Receptors
MEMBRANOUS
SEMICIRCULAR CANALS
(WITHIN SEMICIRCULAR
CANALS)
Also Contains Equilibrium
Receptors
FLUID
ENDOLYMPH: LOCATED WITHIN MEMBRANOUS LABYRINTH
PERILYMPH: LOCATED BETWEEN MEMBRANOUS AND BONY
LABYRINTH
16
FUNCTION
HEARING
Sound Waves Must
be Projected From the
External Environment
into the Cochlear Duct
of the Inner Ear
(Contains Hearing
Receptors)
PROJECTION OF
SOUND WAVES
1. AIR - EXTERNAL EAR
2. BONE - MIDDLE EAR
3. FLUID - INNER EAR
Vibration Creates Sound
Waves
As Sound Waves Pass
Through the External Ear,
They Travel Through Air,
as They Pass Through the
Middle Ear,
They Travel Through Bone,
and
as They Pass Through the
Inner Ear They Travel
Through Fluid
17
STIMULATION OF HEARING
RECEPTORS for CRANIAL NERVE VIII
Movement of the Fluid of the Inner Ear Stimulates the Hearing
Receptors in Cochlear Duct
Mechanoreceptors
CONDUCTION OF NERVE IMPULSES
http://hyperphysics.phyastr.gsu.edu/hbase/sound/anerv.html
(ALONG CRANIAL
NERVE VIII) TO
AUDITORY AREA OF
CEREBRAL CORTEX
Once the Hearing
Receptors are
Stimulated, Nerve
Impulses are
Conducted Along
Cranial Nerve VIII to the
Auditory Area of the
Cerebral Cortex for
Interpretation
18
EQUILIBRIUM
POSITION CHANGES
OF THE HEAD
The Stimulus for
Maintaining the Sense of
Equilibrium is Head
Position
Position Changes of the
Head Sets in Motion the
Fluid of the Inner Ear
EQUILIBRIUM: Utricle & Saccule
Equilibrium Receptors in Utricle, Saccule Most Important in
Static (Stationary) Equilibrium
19
EQUILIBRIUM: Semicircular Canals
Equilibrium Receptors in Membranous SC Canals
Most Important in Dynamic (Moving) Equilibrium
STIMULATION OF EQUILIBRIUM RECEPTORS
(RECEPTORS FOR CRANIAL NERVE VIII)
Movement of the Fluid of the Inner Ear Stimulates the
Equilibrium Receptors in Utricle, Saccule, and Membranous
Semicircular Canals (Mechanoreceptors)
20
CONDUCTION OF NERVE IMPULSES
(ALONG CRANIAL NERVE VIII) TO
CEREBELLUM AND SKELETAL MUSCLES
Once the Equilibrium
Receptors are Stimulated,
Nerve Impulses are
Conducted Along Cranial
Nerve VIII to the Cerebellum
(Equilibrium) and Skeletal
Muscles
VISION: THE EYE
STUCTURE
3 LAYERS OF
EYEBALL
SCLERA
CHOROID
RETINA
21
THE EYE: SCLERA
Outermost Layer
Divided into 2
Portions
SCLERA PROPER:
POSTERIOR
PORTION
White, Tough
CORNEA: ANTERIOR
PORTION
Transparent
THE EYE: CHOROID
Middle Layer
Divided into 2
Portions
CHOROID
PROPER:
POSTERIOR
PORTION
CILIARY BODY,
SUSPENSORY
LIGAMNETS, IRIS:
ANTERIOR
PORTION
22
THE EYE: CHOROID
CHOROID PROPER:
POSTERIOR PORTION
- Vascular
- Contains Black Pigment
THE EYE: CILIARY BODY, SUSPENSORY
LIGAMNETS, IRIS
Anterior Choroid Consists of 3
Structures
Ciliary Body
Thickened Portion of Choroid (Bt
Iris & Choroid Proper)
Contains Ciliary Muscles: Smooth
Muscle that Controls the Shape of
the Lens (Bulges Lens for Near
Vision)
Suspensory Ligaments:
Iris
Hold Lens in Place
Anteriormost Part of Choroid
(Behind Cornea)
Colored Portion of Eye
Shaped Like Doughnut (Hole in
Center is Pupil)
Consists of Smooth Muscle:
Controls Pupil Size
23
THE EYE: RETINA
Innermost Layer of Eye
INCOMPLETE (NO
ANTEROR PORTION);
THIN; NERVOUS TISSUE
Majority of Retina is
Neurons (3 Layers)
NEURONS (Listed in the
Order in Which They
Conduct NI)
PHOTORECEPTOR
NEURONS: RODS &
CONES
BIPOLAR NEURONS
GANGLIONIC NEURONS
THE EYE: RETINA
PHOTORECEPTOR
NEURONS: 1st Layer
Neurons
VISION RECEPTORS:
RODS & CONES
Distal Ends of These
Neurons Contain Vision
Receptors
(Photoreceptors)
2 Kinds Vision Receptors
Based on Shape
Rods: Responsible for
Night Vision
Cones: Responsible for
Day and Color Vision
24
THE EYE: RETINA
THE EYE: RETINA-MACULA
FOVEA CENTRALIS:
MACULA LUTEA
Macula Lutea:
Yellowish Area Approx. in
Center of Retina
Fovea Centralis
Depression in Center of
Macula
Contains Heaviest
Concentration of Cones so
Its the Area of Sharpest
Vision
25
THE EYE: BIPOLAR NEURONS
2nd Layer Neurons
THE EYE: GANGLIONIC
NEURONS
FORM OPTIC DISC/BLIND
SPOT
3rd Layer Neurons
Form Optic Disc (AKA Blind
Spot)
Optic Disc
Where All the Axons of the 3rd
Layer of Neurons Converge
(Then Emerge From Eyeball as
Optic Nerve)
AKA Blind Spot Because
Contains No Receptors, only
Axons
26
THE EYE: CAVITIES
ANTERIOR
CAVITY
Located in Front
of the Lens,
Subdivided into 2
Chambers
POSTERIOR
CAVITY
Located Behind
the Lens, Larger
THE EYE: HUMORS
AQUEOUS HUMOR:
Thin and Watery,
Located (and
Circulates) in Anterior
Cavity
VITREOUS HUMOR:
Thick and Jellylike,
Located in Posterior
Cavity, Helps Hold
Retina in Place
* Humors Maintain
Pressure Within
Eyeball to Prevent
Collapse
27
THE EYE: VITREOUS HUMOR
MUSCLES - Eye Has 2 Kinds
EXTRINSIC (External)
SKELETAL
INTRINSIC (Internal)
Intrinsic Muscles are Part
of the Choroid Layer
SMOOTH
(INVOLUNTARY)
28
EYE MUSCLES: EXTRINSIC
External
Attached to Outer Surface of
Eyeball and Bones of Orbit
SKELETAL (VOLUNTARY)
Function in Voluntary Eye
Movements
NAMES (Total of 6/Eye)
RECTUS MUSCLES
(4): SUPERIOR,
INFERIOR, MEDIAL,
LATERAL
OBLIQUE MUSCLES
(2): SUPERIOR,
INFERIOR
EYE MUSCLES: EXTRINSIC
29
EYE MUSCLES: INTRINSIC
Internal
CHOROID COAT
Intrinsic Muscles are Part
of the Choroid Layer
SMOOTH
(INVOLUNTARY)
NAMES
IRIS: Controls Pupil
Size
CILIARY MUSCLES :
Bulges Lens for Near
Vision
EYE MUSCLES: IRIS
30
ACCESSORY (Assisting)
STRUCTURES
EYEBROWS AND
EYELASHES (Protection)
EYELIDS (CONJUNCTIVA)
Conjunctiva is MUCOUS
Membrane that Lines the
Eyelids and the Front Surface
of the Eyeball
Provides Protection
LACRIMAL APPARATUS
Series of Structures that
Secretes Tears and Drains
Them Across the Surface of
the Eye and into the Nose
Provides Moisture
EYE FUNCTION:
THE MECHANISM OF VISION
Vision Occurs in 3 Steps
1. FORMATION OF
RETINAL IMAGE
2. STIMULATION OF
RECEPTORS
3. CONDUCTION OF
NERVE IMPULSES TO
VISUAL CORTEX
(CEREBRAL
CORTEX)
http://wunmr.wustl.edu/EduD
ev/LabTutorials/Vision/Vision.
html
1
3
2
31
EYE FUNCTION:
THE MECHANISM OF VISION
FORMATION OF
RETINAL IMAGE
First an Image must be
Formed on the Retina
This Requires that Light
Rays be Focused on the
Retina
The Mechanism is
Different for Viewing Far
Objects as Opposed to
Viewing Near Objects
WHEN VIEWING FAR
OBJECTS: REFRACTION
Far Objects: Objects
20 Feet or Further
Formation of a
Retinal Image when
Viewing Far Objects
Requires Refraction
(Bending of Light
Rays)
32
WHEN VIEWING NEAR OBJECTS:
INCREASED REFRACTION REQUIRED
ACCOMMODATION
Near Objects: Objects
Closer than 20 Feet
Formation of a Retinal
Image when Viewing
Near Objects Requires
Increased Refraction
Which Requires
Accommodation
WHEN VIEWING NEAR OBJECTS:
INCREASED REFRACTION REQUIRED
ACCOMMODATION
Focusing near objects
Accommodation:
Changes that Allow for
Near Vision (3)
BULGING OF LENS
CONSTRICTION OF
PUPIL (NEAR REFLEX)
CONVERGENCE OF
EYES
33
Accommodation:
BULGING OF LENS
Ciliary Muscles
Contract, Lens
Bulges Forward
(Causes More Acute
Refraction)
Note:
Lense bulges
When object is
closer
Accommodation:
CONSTRICTION OF PUPIL
NEAR REFLEX
Iris Contracts, Pupil
Constricts (Limits the
Amount of Light that
Enters the Eye Since
More Acute Refraction
Must Occur)
Pupil Constriction when
Viewing Near Objects is
Known as the Near
Reflex
FAR OBJECT
NEAR OBJECT
34
Accommodation:
CONVERGENCE OF EYES
Movement of the 2
Eyeballs Inward
(Causes Light Rays
to Focus on Correct
Regions of the
Retina)
*Note: Reason for Accomodation
Light Rays Enter the
Eye More Divergent
when Viewing Near
Objects
as Opposed to
Parallel when Viewing
Far Objects
Means Light Rays
Must be More Acutely
Bent in Order to get
them Focused on the
Retina
35
STIMULATION OF RECEPTORS
RECEPTORS FOR
CRANIAL NERVE II
Once Light Rays are
Focused on the Retina
and the Image is
Formed
This Causes the Vision
Receptors
(Photoreceptors) to
Become Stimulated
and the NI Begins
STIMULATION OF RECEPTORS:
PHOTOPIGMENTS
Rods and Cones
Contain Photopigments
(Pigments that
Breakdown in Light)
The Photopigments in
Rods are Sensitive to
Dim Light
The Photopigments in
Cones are Sensitive to
Bright Light and Colors
(Red, Green, Blue)
36
Rhodopsin & Change in
Membrane Potential
CONDUCTION OF NERVE IMPULSES
TO VISUAL CORTEX (CEREBRAL CORTEX)
Nerve Impulses are
Conducted Along
Cranial Nerve II
to the Visual Cortex
of the Cerebral
Cortex for
Interpretation
http://wunmr.wustl.edu/EduD
ev/LabTutorials/Vision/Vision.
html
37